docs: add comments above methods

src/two_factor_auth_manager.ts

@@ -6,17 +6,27 @@ import { randomInt } from 'node:crypto'
 export class TwoFactorAuthManager {
   constructor(private config: ResolvedTwoFactorAuthConfig) {}
 
-  generateSecret(account: string): TwoFactorSecret {
+  /**
+   * Generate a `Secret` to the given user information
+   */
+  generateSecret(userInfo: string): TwoFactorSecret {
     return twoFactor.generateSecret({
       name: this.config.issuer,
-      account,
+      account: userInfo,
     })
   }
 
-  generateRecoveryCodes(codeLength = 16) {
-    return Array.from({ length: codeLength }, () => this.generateRecoveryCode(10))
+  /**
+   * Generate `n` recovery codes
+   */
+  generateRecoveryCodes(n = 16) {
+    return Array.from({ length: n }, () => this.generateRecoveryCode(10))
   }
 
+  /**
+   * Verify if the OTP (One-Time password) is
+   * valid to the user `secret`, or if the `recovery codes` includes the `otp`.
+   */
   verifyToken(secret: string = '', token: string, recoveryCodes: string[] = []) {
     const verifyResult = twoFactor.verifyToken(secret, token)
     if (!verifyResult) {
@@ -28,8 +38,11 @@ export class TwoFactorAuthManager {
     return verifyResult.delta === 0 // Valida token atual, não permitindo token já expirado ou token futuro
   }
 
+  /**
+   * Generate a new token from a secret string
+   */
   generateToken(secret: string) {
-    return twoFactor.generateToken(secret)
+    return twoFactor.generateToken(secret)?.token
   }
 
   private generateRandomChar() {
@@ -45,7 +58,6 @@ export class TwoFactorAuthManager {
       recoveryCode += this.generateRandomChar()
     }
 
-    // Inserir um espaço no meio
     const middleIndex = Math.floor(length / 2)
     recoveryCode = `${recoveryCode.substring(0, middleIndex)} ${recoveryCode.substring(middleIndex)}`
 

src/types.ts

@@ -5,6 +5,9 @@ export type ResolvedTwoFactorAuthConfig = {
   issuer: string
 }
 
+/**
+ * `Secret` generated from `generateSecret` method
+ */
 export type TwoFactorSecret = {
   secret: string
   uri: string